This invention relates to locomotive combustion diesel engines, and, more particularly to the fuel filter systems used with the combustion engines for locomotives.
Given the vast terrain that locomotives may travel, the engines and engine accessory parts are often exposed to water. Temperature changes also create condensation within the fuel tank of the locomotive. Accordingly, water may contaminate the fuel tanks of locomotives. The locomotives are preferably operated with a maximum percentage of water to fuel of 0.1% of water by volume, within a fuel tank having a capacity of 5,000 gallons. The water and fuel are usually purged from the tank and engine system on 92 day cycles, and are progressing to 122 days through 180 days.
Fuel filters are used with locomotive internal combustion engines to separate various impurities from fuel including, but not limited to water. The fuel filter includes a filter media supported within a filter housing. As fuel is pumped into the filter, the filter media absorbs water thereby distorting the pore structure and shortening the filter media""s life span.
Fuel filters in locomotives are mounted in a tilted position for maintenance purposes. A drain line connects the fuel filter to the fuel tank. A drain valve is disposed along the drain line between the fuel filter and the fuel tank. The drain valve is typically a ball valve in a normally closed position during operation of the locomotive. In order to maintain the filter, the ball valve is opened to flush out water and from the housing, as well as to empty the fuel tank during routine maintenance of the locomotive.
The maintenance cycle time for the fuel filter may be extended by utilizing a filter coated with a phenolic resin which contains silicone, a hydrophobic organic silicon compound. Accordingly, the silicone consists of hydrocarbon chains which have a strong affinity for the cellulose makeup of the filter media. Water introduced into the fuel filter with fuel is displaced because of the silicone""s attachment to the filter media. The silicone coated filter media actually repels water.
Inasmuch as fuel filters used in connection with a locomotive internal combustion engines are mounted in a tilted position for maintenance purposes, water has a tendency to collect at the bottom wall of the filter housing adjacent an end of the housing. However, different from the previously described drain systems, the fuel filter is in fluid communication with the fuel tank during operation of the locomotive. The filtered water passes from the fuel filter through a drain portal to the fuel tank during operation of the locomotive. The flow of the water from the fuel filter to the fuel tank is maintained at a sufficient rate to minimize the amount of water that will be discharged back into the fuel tank. A strainer may be placed in a drain line to filter large particles that may clog the drain line.
This fuel filter and drain construction has advantages over previous fuel filter systems. Namely, the use of the silicone coated filter prolongs the maintenance cycle of fuel filters. In addition the drain system, permits water from the separated fuel to be discharged during operation of locomotive so water will not remain in the fuel filter to damage the filter media. However, the flow of water is regulated to minimize the volume of water discharged to the fuel tank during operation of the locomotive, and maintain the pressure within the fuel filter housing within acceptable limits so a sufficient differential exists for fuel to flow through the system.